Ligand modification of Cu2ZnSnS4 nanoparticles boosts the performance of low temperature paintable carbon electrode based perovskite solar cells to 17.71%

Abstract

Cu₂ZnSnS₄ (CZTS) nanoparticles have been demonstrated to be a potential hole transporting material for low temperature paintable carbon electrode based perovskite solar cells, yet the reported power conversion efficiency is not satisfactory. Hot injection synthesized CZTS nanoparticles are usually capped with long chain oleylamine, which hampers the charge transportation between CZTS nanoparticles. It is reported that replacing the long chain oleylamine with short chain organic ligand can promote the charge transportation of CZTS nanoparticles. Here, we have demonstrated that CZTS nanoparticles with hexanethiol modification exhibit superior charge transportation properties, which results in better hole extraction capability of the CZTS nanoparticles. Therefore, power conversion efficiency of MAPbI₃ perovskite solar cells employing CZTS hole transporting layer and low temperature paintable carbon electrode is boosted from 14.27% for pristine CZTS nanoparticles to 16.62% for the modified CZTS nanoparticles. When FAPbI₃ is used as alternative light absorbing layer, a champion power conversion efficiency of 17.71% is obtained, which is among one of the highest PCEs for perovskite solar cells employing an inorganic hole transporting layer and a carbon electrode.